It is known to add a device to an electric motor to generate a signal bearing information about the velocity of the motor so that the signal can be used to feedback information to effect some control over the motor behaviour.
It is usual for the velocity signal generator either to be constructed as an integral part of the motor or to be added as an optional extra to the outside of the motor. In either case, existing designs demand that the total package be larger than the motor alone. Furthermore if the velocity signal generator is added on to a standard motor is usually interferes in some way with access to the motor terminals or ventilation of the motor and increases the motor dimensions.
Space within a well designed motor is usually effectively occupied and there is almost no volume free for adding any components.
This invention aims to provide a velocity signal generator within a standard motor without increasing the motor dimensions or adversely affecting the motor construction or performance.
There is a small section conventional commutator motors where space is not used but exists because of the manner of construction of a wound armature. Since segments of the motor commutator have to be connected to the windings on the stack of lamination forming the armature some provision has to be made for hooks on the segments to secure the wire, with subsequent welding or soldering to connect the winding to the segment. This requires that the commutator length be somewhat longer than is required just for making contact with the brushes, which feed power to the commutator. Extending outward radially from that area of the commutator where the hooks exist is usually empty space all the way to the motor boundary formed by the motor housing. This space, which is small, is seldom used.